Advanced Electromagnetics (E-Journal)
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299 research outputs found
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Roughness effect on the efficiency of dimer antenna based biosensor
No full textThe fabrication process of nanodevices is continually improved. However, most of the nanodevices, such as biosensors present rough surfaces with mean roughness of some nanometers even if the deposition rate of material is more controlled. The effect of roughness on performance of biosensors was fully addressed for plane biosensors and gratings, but rarely addressed for biosensors based on Local Plasmon Resonance. The purpose of this paper is to evaluate numerically the influence of nanometric roughness on the efficiency of a dimer nano-biosensor (two levels of roughness are considered). Therefore, we propose a general numerical method, that can be applied to any other nanometric shape, to take into account the roughness in a three dimensional model. The study focuses on both the far-field, which corresponds to the experimental detected data, and the near-field, responsible for exciting and then detecting biological molecules. The results suggest that the biosensor efficiency is highly sensitive to the surface roughness. The roughness can produce important shifts of the extinction efficiency peak and a decrease of its amplitude resulting from changes in the distribution of near-field and absorbed electric field intensities
Efficient Compression of Far Field Matrices in Multipole Algorithms based on Spherical Harmonics and Radiating Modes
No full textThis paper proposes a compression of far field matrices in the fast multipole method and its multilevel extension for electromagnetic problems. The compression is based on a spherical harmonic representation of radiation patterns in conjunction with a radiating mode expression of the surface current. The method is applied to study near field effects and the far field of an antenna placed on a ship surface. Furthermore, the electromagnetic scattering of an electrically large plate is investigated. It is demonstrated, that the proposed technique leads to a significant memory saving, making multipole algorithms even more efficient without compromising the accuracy
On the Evaluation of the Shielding Effectiveness of Electrically Large Enclosure
No full textThe shielding effectiveness (SE) has become afundamental step in testing active or passive electricdevices. The Reverberating Chamber (RC) is a wellestablishedmethod for determining the SE since has theadvantage to expose the material to a more realisticenvironment. In this paper the SEe of electrically largeenclosure with a metallic mesh grid in a RC is evaluated.Enclosures made with metallic mesh are considered. Inparticular, it is shown that the SE of a material is unable toprovide complete information for the SEe of electricallylarge enclosure made with the same material. Moreover,this latter one is related to the loading conditions within theenclosure itself. Measurements accomplished at RC of theUniversità di Napoli Parthenope (formerly IstitutoUniversitario Navale, IUN) confirm the physical soundnessof the proposed approach
Dilation of nanonatennas induced by an electromagnetic source
No full textThe illumination of plasmonic mesostructures produces high confinement of light in their vicinity. This confinement of light can be enhanced in the gap between the two metallic nanorods of a nanonantenna, in particular for the design of biosensors. The nanometric gap can be reduced if the elevation of temperature of the nanonantenna is sufficient, and therefore the fine tuning of the sensor requires the description of the photo-thermal induced dilation. The multiphysics problem associated to such photo-thermal and mechanical effects is modeled through a Finite Element Method (FEM). The problem consists in computing the electromagnetic field, the temperature and the induced dilation surface. This contribution consists in discussing the numerical efficiencies of a sequential, and a coupled approaches, especially in terms of adaptive meshing of the space of computation. The relationship between the field enhancement and the reduction of the gap is studied. Finally the validity of the 2D multiphysic model is discussed
Design, Manufacturing and characterization of integrated inductors with magnetic layers for DC-DC converter
No full textThis paper presents the conception, fabrication and characterization of integrated inductors containing magnetic layers. We require different steps of micro-technologies: preparation of glass and ferrite substrates, RF sputtering, photolithography, etching and finally electroplating techniques for copper and gold films. The geometrical magnitudes are determined by using HFSS simulator software. The measurements performed at low and high frequencies (up to 1 GHz) permit to verify the correlation between experiment and simulation results. The inductance of the manufactured spiral inductor is about 200 nH and it is constant from low frequency up to 0.9 GHz
Comparative study of optical properties of the one-dimensional multilayer Period-Doubling and Thue-Morse quasi-periodic photonic crystals
No full textThe last decades have witnessed the growing interest in the use of photonic crystal as a new material that can be used to control electromagnetic wave. Actually, not only the periodic structures but also the quasi-periodic systems have become significant structures of photonic crystals. This work deals with optical properties of dielectric Thue-Morse multilayer and Period-Doubling multilayer. We use the so-called Transfer Matrix Method (TMM) to determine the transmission spectra of the structures. Based on the representation of the transmittance spectra in the visible range a comparative analysis depending on the iteration number, number of layers and incidence angle is presented
Directive properties of active coated nano-particles
No full textThe directivities of the fields radiated by a variety of cylindrical and spherical active coated nano-particles, which are excited by their respective sources of illumination at optical frequencies, are investigated. Particular attention is devoted to the influence of the source location and optical gain constant on the directivities. While significant variations in the directivities are realized in the cylindrical cases for different source locations within and slightly outside the nano-particles and values of the optical gain constant, the corresponding spherical cases exhibit negligible differences
Multiband Slot-Based Dual Composite Right/Left-Handed Transmission Line
No full textA dual Composite Right-/Left-Handed Transmission Line (CRLH TL) implementation that presents multiband behaviour is proposed in this contribution. The artificial TL is realized by loading a host microstrip line with alternate rectangular stubs and slots. The required series and shunt immittances are respectively provided by the slot and the stub. Due to the distributed nature of these immittances, the resultant phase response presents theoretically infinite RH and LH alternate bands, thus being appropriate for multiband applications. The design methodology is described with the help of a proposed TLs-based equivalent circuit and highlights the simplicity for balance condition. Full wave simulated results of the dispersion characteristics and frequency response of a unit-cell and a three-cells structure are presented
Surface Plasmon - Guided Mode strong coupling
No full textIt is shown that it is possible to realize strong coupling between a surface plasmon and a guided mode in a layered structure. The dispersion relation of such a structure is obtained through the S-matrix algorithm combined with the Cauchy integral technique that allows for rigorous computations of complex poles. The strong coupling is demonstrated by the presence of an anticrossing in the dispersion diagram and simultaneously by the presence of a crossing in the loss diagram. The temporal characteristics of the different modes and the decay of the losses in the propagation of the hybridized surface plasmons are studied
Frequency Dependent Model of Leakage Inductance for Magnetic Components
No full textTheoretical methods for the calculation of winding losses with respect to frequency have been well documented, but the variation in leakage inductance of magnetic components due to frequency has been less well addressed. In this paper Dowell’s well-known theoretical approach is tested using measurements and finite element analyses. The results presented show deficiencies in the accuracy of models generated using Dowell’s approach and highlight the trade-offs between model complexity, simulation time and accuracy when the finite element analysis method is applied. An alternative behavioral model is presented which models the frequency variation in leakage inductance accurately, is easy to characterize from simple measurements or calculations and is robust